The stability, steerability and braking performance of heavy duty vehicles and vehicles combinations have become more important for traffic safety as demand on speed and load performance has increased. For about 20 years the Swedish Road and Traffic Institute (VTI) has carried out experimental and theoretical research concerning these factors with the aim of investigating the state of the art, identifying means of improving performance and proposing minimum performance requirements. The research has primarily dealth with the following problem areas: dynamic yaw stability and handling properties dealth at constant speed; roll over stability; stability, steerability and braking efficiency in braking manoeuvres primarily with vehicles equipped with anti-lock braking systems under winter conditions; space requirements at low and high speed; and tyre characteristics. Large complex test facilities, such as a truck tyre test facility with ice testing capacity and a moving base truck driving simulator, have been developed by VTI. The aim of this paper is to give an updated and expanded version of an earlier review (Nordström, 1989) of these research and development activities and give the present VTI position concerning methods of testing and desirable performance requirements.
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